1. Field of the Invention
The present invention is related to a bridge expulsion joint, and more particularly, to a bridge expansion joint for connecting upper plates of a bridge in such a way that it enables the upper plates of the bridge to stretch or to be contracted in order to counteract the contraction and expansion of the bridge accenting to the changes in temperature, which is capable of preventing the accumulation of foreign substances and of easily discharging them to the outside.
2. Description of the Prior Art
As is well known, the bridge expansion joint may be designed for sufficiently supporting an external load under the service limit state and the ultimate limit state and for obtaining a sufficient durability, a good surface-smoothness and a satisfactory water-tightness by meeting a fundamental requirement for the fatigue limit situation.
Generally, in the long bridge structure having a plurality of bridge piers, a bridge deck section may be divided into a number of parts along the longitudinal direction of the bridge structure in order to counteract the contraction and expansion of the bridge according to the changes in temperature. The bridge expansion joint may be installed between the divided parts of the bridge deck section.
For example, the bridge expansion joint installed between the bridge deck sections of the bridge is an attachment for the bridge and it can accommodate the behavior of the bridge when the bridge is contracted or stretches in accordance with the changes in temperature.
The bridge expansion joint according to the prior art as described above may include a finger block of which a plurality of fingers are installed in the manner of the double structure such as the sliding-cantilever type structure. Due to this structure, although water or foreign substances is flowed between the fingers, it will not be dropped below the bridge deck sections and thereby resulting in safe protection of the surrounding structures.
The bridge expansion joint having the finger block according to the prior art can move along the direction of a vehicle's travel on the roadway over a range of expansion and contraction thereof when an earthquake strikes. However, it cannot move along a horizontal direction that is perpendicular to the direction of a vehicle's travel.
Another drawback of this conventional bridge expansion is that any structure for allowing a road packaging to be successfully and smoothly performed may be relatively insufficient and thereby resulting in the occurrence of the great noise and the vibration. Consequently, there is a disadvantage that driving performance of the vehicle is likely to deteriorate.
A variety of endeavors for solving the above problems have been proposed. One approach is, the refraction-type expansion and contraction joint apparatus for a bridge has been proposed on Korean Patent No. 10-0921415 issued to JINHYUNG CONSTRUCTION Co., Ltd, on Oct. 6, 2009. This joint apparatus of which a pair of link members is disposed between the bridge deck sections with opposite each other can move along the X-axis direction or the Y-axis direction in accordance with the behavior of the bridge. One drawback of this conventional apparatus is that the expansion and contraction to be embodied by means of the link members may be limited within a predetermined range. Accordingly, it is difficult to adopt this joint apparatus for any extremely long length of bridge.
Nevertheless, if the conventional joint apparatus is manufactured in such a way that the length of link members is relatively increased so as to be used for the long span bridge, then the bridge may be sagging or drooping at a middle portion of the link member or at the hinge engagement section due to the increase of the link member's weight. As a result, the link member cannot smoothly rotate. Because any technology for previously preventing the phenomenon of sagging or drooping has not been developed yet, it would seem likely that the above joint apparatus cannot be smoothly applied to the long span bridge.
Because the conventional joint apparatus of which the link members are fixed by only using the hinge does not have any means for reinforcing the combining state of the hinge, it is difficult to reliably maintain the hinge engagement.
In the meantime, the conventional joint apparatus is provided with the means for preventing foreign substances from being introduced, which may be made of flexible materials and ma be installed between the side plates disposed at the lower portions of the links in such a manner that it makes them to be connected each other.
There is high probability of this joint apparatus being received the repetitive load generated when the expansion and the contraction is repeatedly occurred in accordance with the behavior of the bridge deck section. Because foreign substances that have already been introduced will solidify over time, it would seem likely that the above joint apparatus cannot perform the proper function thereof and may even be destroyed in severe cases. Furthermore, it would seem likely that the rotational operation of the link may be hindered by foreign substances. Consequently, there are problems that the maintenance control is needed when things go wrong or break downs occur and also it is required to frequently replace the components of the joint apparatus.
Meanwhile, the links of the conventional joint apparatus can rotate with each other due to the operation of the hinge bolt. However, because water can enter certain apertures provided around the hinge bolt in the conventional joint apparatus, it would seem likely that it is impossible to prevent the water leak beforehand.